Generally, a cathode ray tube (CRT) includes a panel with an inner phosphor screen, a funnel connected to the rear of the panel with a deflection yoke mounted around the outer circumference thereof, and a neck connected to the rear of the funnel with an electron gun mounted therein.
The phosphor screen has red, green and blue phosphor layers, and the electron gun emits three rays of electron beams toward the phosphor screen corresponding to respective three colors, red, green, and blue. The deflection yoke deflects the electron beams progressing in the funnel such that they scan the phosphor screen.
A shadow mask is fitted within the panel as a color selection electrode while being spaced apart from the phosphor screen. The shadow mask has a plurality of electron beam passage holes, and selects the three rays of electron beams emitted from the electron gun such that they land on the appropriate phosphor layer.
With the above-structured cathode ray tube, the panel may have a flat outer surface and a curved inner surface with a predetermined curvature. It has been proposed that the central thickness of the panel should be reduced to enhance the screen brightness and reduce the weight. However, in this case, X rays harmful to human body are emitted from the cathode ray tube due to the reduced central thickness. Therefore, a limit is imposed on reducing the thickness of the panel.
Furthermore, when the inner surface of the panel is varied in shape, the curvature characteristic of the shadow mask should be varied accordingly. However, the curvature characteristic of the shadow mask is related to the impact resistance characteristic thereof with respect to the external impact, such as accidental dropping of the panel. Consequently, when the inner surface of the panel and the curvature characteristic of the shadow mask are determined without considering the impact resistance characteristic of the shadow mask, the impact resistance characteristic is deteriorated, and thus decreasing the reliability of the device.